import torch
import torch.nn as nn
import torch.nn.functional as F
import numpy as np
from timm.models.layers import DropPath, trunc_normal_
import torch.utils.checkpoint as checkpoint
from functools import reduce, lru_cache
from operator import mul
from einops import rearrange


__all__ = ["AllPatchEmbed", "PatchRecover", "BasicLayer", "SwinTransformerLayer"]


class Mlp(nn.Module):
    """ Multilayer perceptron."""

    def __init__(self, in_features, hidden_features=None, out_features=None, act_layer=nn.GELU, drop=0.):
        super().__init__()
        out_features = out_features or in_features
        hidden_features = hidden_features or in_features
        self.fc1 = nn.Linear(in_features, hidden_features)
        self.act = act_layer()
        self.fc2 = nn.Linear(hidden_features, out_features)
        self.drop = nn.Dropout(drop)

    def forward(self, x):
        x = self.fc1(x)
        x = self.act(x)
        x = self.drop(x)
        x = self.fc2(x)
        x = self.drop(x)
        return x


def swin_window_partition(x, window_size):
    """
    Args:
        x: (B, D, H, W, C)
        window_size (tuple[int]): window size

    Returns:
        windows: (B*num_windows, window_size*window_size, C)
    """
    B, D, H, W, C = x.shape
    x = x.view(B, D // window_size[0], window_size[0], H // window_size[1], window_size[1], W // window_size[2], window_size[2], C)
    windows = x.permute(0, 1, 3, 5, 2, 4, 6, 7).contiguous().view(-1, reduce(mul, window_size), C)
    return windows


def swin_window_reverse(windows, window_size, B, D, H, W):
    """
    Args:
        windows: (B*num_windows, window_size, window_size, C)
        window_size (tuple[int]): Window size
        H (int): Height of image
        W (int): Width of image

    Returns:
        x: (B, D, H, W, C)
    """
    x = windows.view(B, D // window_size[0], H // window_size[1], W // window_size[2], window_size[0], window_size[1], window_size[2], -1)
    x = x.permute(0, 1, 4, 2, 5, 3, 6, 7).contiguous().view(B, D, H, W, -1)
    return x


def get_window_size(x_size, window_size, shift_size=None):
    use_window_size = list(window_size)
    if shift_size is not None:
        use_shift_size = list(shift_size)
    for i in range(len(x_size)):
        if x_size[i] <= window_size[i]:
            use_window_size[i] = x_size[i]
            if shift_size is not None:
                use_shift_size[i] = 0

    if shift_size is None:
        return tuple(use_window_size)
    else:
        return tuple(use_window_size), tuple(use_shift_size)


class WindowAttention3D(nn.Module):
    """ Window based multi-head self attention (W-MSA) module with relative position bias.
    It supports both of shifted and non-shifted window.
    Args:
        dim (int): Number of input channels.
        window_size (tuple[int]): The temporal length, height and width of the window.
        num_heads (int): Number of attention heads.
        qkv_bias (bool, optional):  If True, add a learnable bias to query, key, value. Default: True
        qk_scale (float | None, optional): Override default qk scale of head_dim ** -0.5 if set
        attn_drop (float, optional): Dropout ratio of attention weight. Default: 0.0
        proj_drop (float, optional): Dropout ratio of output. Default: 0.0
    """

    def __init__(self, dim, window_size, num_heads, qkv_bias=False, qk_scale=None, attn_drop=0., proj_drop=0., cross=False):

        super().__init__()
        self.dim = dim
        self.window_size = window_size  # Wd, Wh, Ww
        self.num_heads = num_heads
        head_dim = dim // num_heads
        self.scale = qk_scale or head_dim ** -0.5
        self.cross = cross

        # define a parameter table of relative position bias
        self.relative_position_bias_table = nn.Parameter(
            torch.zeros((2 * window_size[0] - 1) * (2 * window_size[1] - 1) * (2 * window_size[2] - 1), num_heads))  # 2*Wd-1 * 2*Wh-1 * 2*Ww-1, nH

        # get pair-wise relative position index for each token inside the window
        coords_d = torch.arange(self.window_size[0])
        coords_h = torch.arange(self.window_size[1])
        coords_w = torch.arange(self.window_size[2])
        coords = torch.stack(torch.meshgrid(coords_d, coords_h, coords_w))  # 3, Wd, Wh, Ww
        coords_flatten = torch.flatten(coords, 1)  # 3, Wd*Wh*Ww
        relative_coords = coords_flatten[:, :, None] - coords_flatten[:, None, :]  # 3, Wd*Wh*Ww, Wd*Wh*Ww
        relative_coords = relative_coords.permute(1, 2, 0).contiguous()  # Wd*Wh*Ww, Wd*Wh*Ww, 3
        relative_coords[:, :, 0] += self.window_size[0] - 1  # shift to start from 0
        relative_coords[:, :, 1] += self.window_size[1] - 1
        relative_coords[:, :, 2] += self.window_size[2] - 1

        relative_coords[:, :, 0] *= (2 * self.window_size[1] - 1) * (2 * self.window_size[2] - 1)
        relative_coords[:, :, 1] *= (2 * self.window_size[2] - 1)
        relative_position_index = relative_coords.sum(-1)  # Wd*Wh*Ww, Wd*Wh*Ww
        self.register_buffer("relative_position_index", relative_position_index)

        if self.cross:
            self.q = nn.Linear(dim, dim, bias=qkv_bias)
            self.k = nn.Linear(dim, dim, bias=qkv_bias)
            self.v = nn.Linear(dim, dim, bias=qkv_bias)
        else:
            self.qkv = nn.Linear(dim, dim * 3, bias=qkv_bias)

        self.attn_drop = nn.Dropout(attn_drop)
        self.proj = nn.Linear(dim, dim)
        self.proj_drop = nn.Dropout(proj_drop)

        trunc_normal_(self.relative_position_bias_table, std=.02)
        self.softmax = nn.Softmax(dim=-1)

    def forward(self, x, mask=None, condition=None):
        """ Forward function.
        Args:
            x: input features with shape of (num_windows*B, N, C)
            mask: (0/-inf) mask with shape of (num_windows, N, N) or None
        """
        B_, N, C = x.shape
        if self.cross:
            q = self.q(x).reshape(B_, N, self.num_heads, C // self.num_heads).transpose(1,2)
            k = self.k(condition).reshape(B_, N, self.num_heads, C // self.num_heads).transpose(1,2)
            v = self.v(condition).reshape(B_, N, self.num_heads, C // self.num_heads).transpose(1,2)
        else:
            qkv = self.qkv(x).reshape(B_, N, 3, self.num_heads, C // self.num_heads).permute(2, 0, 3, 1, 4)
            q, k, v = qkv[0], qkv[1], qkv[2]  # B_, nH, N, C

        q = q * self.scale
        attn = q @ k.transpose(-2, -1)

        relative_position_bias = self.relative_position_bias_table[self.relative_position_index[:N, :N].reshape(-1)].reshape(
            N, N, -1)  # Wd*Wh*Ww,Wd*Wh*Ww,nH
        relative_position_bias = relative_position_bias.permute(2, 0, 1).contiguous()  # nH, Wd*Wh*Ww, Wd*Wh*Ww
        attn = attn + relative_position_bias.unsqueeze(0) # B_, nH, N, N

        if mask is not None:
            nW = mask.shape[0]
            attn = attn.view(B_ // nW, nW, self.num_heads, N, N) + mask.unsqueeze(1).unsqueeze(0)
            attn = attn.view(-1, self.num_heads, N, N)
            attn = self.softmax(attn)
        else:
            attn = self.softmax(attn)

        attn = self.attn_drop(attn)

        x = (attn @ v).transpose(1, 2).reshape(B_, N, C)
        x = self.proj(x)
        x = self.proj_drop(x)
        return x


class SwinTransformerBlock3D(nn.Module):
    """ Swin Transformer Block.

    Args:
        dim (int): Number of input channels.
        num_heads (int): Number of attention heads.
        window_size (tuple[int]): Window size.
        shift_size (tuple[int]): Shift size for SW-MSA.
        mlp_ratio (float): Ratio of mlp hidden dim to embedding dim.
        qkv_bias (bool, optional): If True, add a learnable bias to query, key, value. Default: True
        qk_scale (float | None, optional): Override default qk scale of head_dim ** -0.5 if set.
        drop (float, optional): Dropout rate. Default: 0.0
        attn_drop (float, optional): Attention dropout rate. Default: 0.0
        drop_path (float, optional): Stochastic depth rate. Default: 0.0
        act_layer (nn.Module, optional): Activation layer. Default: nn.GELU
        norm_layer (nn.Module, optional): Normalization layer.  Default: nn.LayerNorm
    """

    def __init__(self, dim, num_heads, window_size=(2,7,7), shift_size=(0,0,0),
                 mlp_ratio=4., qkv_bias=True, qk_scale=None, drop=0., attn_drop=0., drop_path=0.,
                 act_layer=nn.GELU, norm_layer=nn.LayerNorm, cross=False, use_checkpoint=False):
        super().__init__()
        self.dim = dim
        self.num_heads = num_heads
        self.window_size = window_size
        self.shift_size = shift_size
        self.mlp_ratio = mlp_ratio
        self.use_checkpoint=use_checkpoint
        self.cross = cross

        assert 0 <= self.shift_size[0] < self.window_size[0], "shift_size must in 0-window_size"
        assert 0 <= self.shift_size[1] < self.window_size[1], "shift_size must in 0-window_size"
        assert 0 <= self.shift_size[2] < self.window_size[2], "shift_size must in 0-window_size"

        self.norm1 = norm_layer(dim)
        self.attn = WindowAttention3D(
            dim, window_size=self.window_size, num_heads=num_heads,
            qkv_bias=qkv_bias, qk_scale=qk_scale, attn_drop=attn_drop, proj_drop=drop, cross=cross)

        self.drop_path = DropPath(drop_path) if drop_path > 0. else nn.Identity()
        self.norm2 = norm_layer(dim)
        mlp_hidden_dim = int(dim * mlp_ratio)
        self.mlp = Mlp(in_features=dim, hidden_features=mlp_hidden_dim, act_layer=act_layer, drop=drop)

        if self.cross:
            self.norm_condition = norm_layer(dim)

    def forward_part1(self, x, mask_matrix, condition):
        B, D, H, W, C = x.shape
        window_size, shift_size = get_window_size((D, H, W), self.window_size, self.shift_size)

        x = self.norm1(x)
        # pad feature maps to multiples of window size
        pad_l = pad_t = pad_d0 = 0
        pad_d1 = (window_size[0] - D % window_size[0]) % window_size[0]
        pad_b = (window_size[1] - H % window_size[1]) % window_size[1]
        pad_r = (window_size[2] - W % window_size[2]) % window_size[2]
        x = F.pad(x, (0, 0, pad_l, pad_r, pad_t, pad_b, pad_d0, pad_d1))
        _, Dp, Hp, Wp, _ = x.shape
        # cyclic shift
        if any(i > 0 for i in shift_size):
            shifted_x = torch.roll(x, shifts=(-shift_size[0], -shift_size[1], -shift_size[2]), dims=(1, 2, 3))
            attn_mask = mask_matrix
        else:
            shifted_x = x
            attn_mask = None
        # partition windows
        x_windows = swin_window_partition(shifted_x, window_size)  # B*nW, Wd*Wh*Ww, C
        condition_windows = condition

        if self.cross:
            condition = self.norm_condition(condition)
            condition = F.pad(condition, (0, 0, pad_l, pad_r, pad_t, pad_b, pad_d0, pad_d1))
            if any(i > 0 for i in shift_size):
                shifted_condition = torch.roll(condition, shifts=(-shift_size[0], -shift_size[1], -shift_size[2]), dims=(1, 2, 3))
            else:
                shifted_condition = condition
            condition_windows = swin_window_partition(shifted_condition, window_size)

        # W-MSA/SW-MSA
        attn_windows = self.attn(x_windows, mask=attn_mask, condition=condition_windows)  # B*nW, Wd*Wh*Ww, C
        # merge windows
        attn_windows = attn_windows.view(-1, *(window_size+(C,)))
        shifted_x = swin_window_reverse(attn_windows, window_size, B, Dp, Hp, Wp)  # B D' H' W' C
        # reverse cyclic shift
        if any(i > 0 for i in shift_size):
            x = torch.roll(shifted_x, shifts=(shift_size[0], shift_size[1], shift_size[2]), dims=(1, 2, 3))
        else:
            x = shifted_x

        if pad_d1 >0 or pad_r > 0 or pad_b > 0:
            x = x[:, :D, :H, :W, :].contiguous()
        return x

    def forward_part2(self, x):
        return self.drop_path(self.mlp(self.norm2(x)))

    def forward(self, x, mask_matrix, condition=None):
        """ Forward function.

        Args:
            x: Input feature, tensor size (B, D, H, W, C).
            mask_matrix: Attention mask for cyclic shift.
        """

        shortcut = x
        if self.use_checkpoint:
            x = checkpoint.checkpoint(self.forward_part1, x, mask_matrix, condition)
        else:
            x = self.forward_part1(x, mask_matrix, condition)
        x = shortcut + self.drop_path(x)

        if self.use_checkpoint:
            x = x + checkpoint.checkpoint(self.forward_part2, x)
        else:
            x = x + self.forward_part2(x)

        return x


# cache each stage results
@lru_cache()
def compute_mask(D, H, W, window_size, shift_size, device):
    img_mask = torch.zeros((1, D, H, W, 1), device=device)  # 1 Dp Hp Wp 1
    cnt = 0
    for d in slice(-window_size[0]), slice(-window_size[0], -shift_size[0]), slice(-shift_size[0],None):
        for h in slice(-window_size[1]), slice(-window_size[1], -shift_size[1]), slice(-shift_size[1],None):
            for w in slice(-window_size[2]), slice(-window_size[2], 0), slice(0,None):
                img_mask[:, d, h, w, :] = cnt
                cnt += 1
    mask_windows = swin_window_partition(img_mask, window_size)  # nW, ws[0]*ws[1]*ws[2], 1
    mask_windows = mask_windows.squeeze(-1)  # nW, ws[0]*ws[1]*ws[2]
    attn_mask = mask_windows.unsqueeze(1) - mask_windows.unsqueeze(2)
    attn_mask = attn_mask.masked_fill(attn_mask != 0, float(-100.0)).masked_fill(attn_mask == 0, float(0.0))
    return attn_mask


class GatedCrossAttention(nn.Module):
    """ A basic Swin Transformer layer for one stage.

    Args:
        dim (int): Number of feature channels
        depth (int): Depths of this stage.
        num_heads (int): Number of attention head.
        window_size (tuple[int]): Local window size. Default: (1,7,7).
        mlp_ratio (float): Ratio of mlp hidden dim to embedding dim. Default: 4.
        qkv_bias (bool, optional): If True, add a learnable bias to query, key, value. Default: True
        qk_scale (float | None, optional): Override default qk scale of head_dim ** -0.5 if set.
        drop (float, optional): Dropout rate. Default: 0.0
        attn_drop (float, optional): Attention dropout rate. Default: 0.0
        drop_path (float | tuple[float], optional): Stochastic depth rate. Default: 0.0
        norm_layer (nn.Module, optional): Normalization layer. Default: nn.LayerNorm
        downsample (nn.Module | None, optional): Downsample layer at the end of the layer. Default: None
    """

    def __init__(self, dim, num_heads, window_size=(1,7,7), mlp_ratio=4., qkv_bias=True, qk_scale=None,
                 drop=0., attn_drop=0., drop_path=0., norm_layer=nn.LayerNorm, use_checkpoint=False):
        super().__init__()
        self.window_size = window_size
        self.shift_size = tuple(i // 2 for i in window_size)
        self.use_checkpoint = use_checkpoint

        # build blocks  
        self.back1 = SwinTransformerBlock3D(dim=dim, num_heads=num_heads, window_size=window_size, shift_size=(0,0,0),
                                            mlp_ratio=mlp_ratio, qkv_bias=qkv_bias, qk_scale=qk_scale, drop=drop, attn_drop=attn_drop, 
                                            drop_path=drop_path, norm_layer=norm_layer, cross=True, use_checkpoint=use_checkpoint)
        self.back2 = SwinTransformerBlock3D(dim=dim, num_heads=num_heads, window_size=window_size, shift_size=self.shift_size,
                                            mlp_ratio=mlp_ratio, qkv_bias=qkv_bias, qk_scale=qk_scale, drop=drop, attn_drop=attn_drop, 
                                            drop_path=drop_path, norm_layer=norm_layer, cross=True, use_checkpoint=use_checkpoint)
        self.obser1 = SwinTransformerBlock3D(dim=dim, num_heads=num_heads, window_size=window_size, shift_size=(0,0,0),
                                            mlp_ratio=mlp_ratio, qkv_bias=qkv_bias, qk_scale=qk_scale, drop=drop, attn_drop=attn_drop, 
                                            drop_path=drop_path, norm_layer=norm_layer, cross=True, use_checkpoint=use_checkpoint)
        self.obser2 = SwinTransformerBlock3D(dim=dim, num_heads=num_heads, window_size=window_size, shift_size=self.shift_size,
                                            mlp_ratio=mlp_ratio, qkv_bias=qkv_bias, qk_scale=qk_scale, drop=drop, attn_drop=attn_drop, 
                                            drop_path=drop_path, norm_layer=norm_layer, cross=True, use_checkpoint=use_checkpoint)
        self.gate = nn.Conv3d(dim, dim, 1)

    def forward(self, x1, x2, gate):
        """ Forward function.

        Args:
            x: Input feature, tensor size (B, C, D, H, W).
        """
        # calculate attention mask for SW-MSA
        B, C, D, H, W = x1.shape
        window_size, shift_size = get_window_size((D,H,W), self.window_size, self.shift_size)
        x1 = rearrange(x1, 'b c d h w -> b d h w c')
        x2 = rearrange(x2, 'b c d h w -> b d h w c')
        gate = rearrange(gate, 'b c d h w -> b d h w c')
        Dp = int(np.ceil(D / window_size[0])) * window_size[0]
        Hp = int(np.ceil(H / window_size[1])) * window_size[1]
        Wp = int(np.ceil(W / window_size[2])) * window_size[2]
        attn_mask = compute_mask(Dp, Hp, Wp, window_size, shift_size, x1.device)
        
        x1_mid = x1 * (1 - gate) + self.back1(x1 * gate, attn_mask, x2)
        x2_mid = self.obser1(x2, attn_mask, x1)
        x1 = x1_mid * (1 - gate) + self.back2(x1_mid * gate, attn_mask, x2_mid)
        x2 = self.obser2(x2_mid, attn_mask, x1_mid)

        x1 = rearrange(x1, 'b d h w c -> b c d h w')
        x2 = rearrange(x2, 'b d h w c -> b c d h w')
        gate = rearrange(gate, 'b d h w c -> b c d h w')
        gate = torch.sigmoid(self.gate(gate))
        return [x1, x2, gate]


class SwinTransformerLayer(nn.Module):
    """ A basic Swin Transformer layer for one stage.

    Args:
        dim (int): Number of feature channels
        depth (int): Depths of this stage.
        num_heads (int): Number of attention head.
        window_size (tuple[int]): Local window size. Default: (1,7,7).
        mlp_ratio (float): Ratio of mlp hidden dim to embedding dim. Default: 4.
        qkv_bias (bool, optional): If True, add a learnable bias to query, key, value. Default: True
        qk_scale (float | None, optional): Override default qk scale of head_dim ** -0.5 if set.
        drop (float, optional): Dropout rate. Default: 0.0
        attn_drop (float, optional): Attention dropout rate. Default: 0.0
        drop_path (float | tuple[float], optional): Stochastic depth rate. Default: 0.0
        norm_layer (nn.Module, optional): Normalization layer. Default: nn.LayerNorm
        downsample (nn.Module | None, optional): Downsample layer at the end of the layer. Default: None
    """

    def __init__(self,
                 dim,
                 depth,
                 num_heads,
                 window_size=(1,7,7),
                 mlp_ratio=4.,
                 qkv_bias=True,
                 qk_scale=None,
                 drop=0.,
                 attn_drop=0.,
                 drop_path=0.,
                 norm_layer=nn.LayerNorm,
                 use_checkpoint=False):
        super().__init__()
        self.window_size = window_size
        self.shift_size = tuple(i // 2 for i in window_size)
        self.depth = depth
        self.use_checkpoint = use_checkpoint

        # build blocks
        self.blocks = nn.ModuleList([
            SwinTransformerBlock3D(
                dim=dim,
                num_heads=num_heads,
                window_size=window_size,
                shift_size=(0,0,0) if (i % 2 == 0) else self.shift_size,
                mlp_ratio=mlp_ratio,
                qkv_bias=qkv_bias,
                qk_scale=qk_scale,
                drop=drop,
                attn_drop=attn_drop,
                drop_path=drop_path[i] if isinstance(drop_path, list) else drop_path,
                norm_layer=norm_layer,
                use_checkpoint=use_checkpoint,
            )
            for i in range(depth)])

    def forward(self, x):
        """ Forward function.

        Args:
            x: Input feature, tensor size (B, C, D, H, W).
        """
        # calculate attention mask for SW-MSA
        B, C, D, H, W = x.shape
        window_size, shift_size = get_window_size((D,H,W), self.window_size, self.shift_size)
        x = rearrange(x, 'b c d h w -> b d h w c')
        Dp = int(np.ceil(D / window_size[0])) * window_size[0]
        Hp = int(np.ceil(H / window_size[1])) * window_size[1]
        Wp = int(np.ceil(W / window_size[2])) * window_size[2]
        attn_mask = compute_mask(Dp, Hp, Wp, window_size, shift_size, x.device)
        for blk in self.blocks:
            x = blk(x, attn_mask)
        x = x.view(B, D, H, W, -1)
        x = rearrange(x, 'b d h w c -> b c d h w')
        return x


class PatchMerging(nn.Module):
    """ Patch Merging Layer

    Args:
        dim (int): Number of input channels.
        norm_layer (nn.Module, optional): Normalization layer.  Default: nn.LayerNorm
    """
    def __init__(self, dim, norm_layer=nn.LayerNorm):
        super().__init__()
        self.dim = dim
        self.reduction = nn.Linear(4 * dim, 2 * dim, bias=False)
        self.norm = norm_layer(4 * dim)

    def forward(self, x):
        """ Forward function.

        Args:
            x: Input feature, tensor size (B, D, H, W, C).
        """
        B, D, H, W, C = x.shape

        # padding
        pad_input = (H % 2 == 1) or (W % 2 == 1)
        if pad_input:
            x = F.pad(x, (0, 0, 0, W % 2, 0, H % 2))

        x0 = x[:, :, 0::2, 0::2, :]  # B D H/2 W/2 C
        x1 = x[:, :, 0::2, 1::2, :]  # B D H/2 W/2 C
        x2 = x[:, :, 1::2, 0::2, :]  # B D H/2 W/2 C
        x3 = x[:, :, 1::2, 1::2, :]  # B D H/2 W/2 C
        x = torch.cat([x0, x1, x2, x3], -1)  # B D H/2 W/2 4*C

        x = self.norm(x)
        x = self.reduction(x)

        return x
    

class AllPatchMerging(nn.Module):
    """ Patch Merging Layer

    Args:
        dim (int): Number of input channels.
        norm_layer (nn.Module, optional): Normalization layer.  Default: nn.LayerNorm
    """
    def __init__(self, dim, norm_layer=nn.LayerNorm):
        super().__init__()
        self.dim = dim
        self.merge1 = PatchMerging(dim, norm_layer)
        self.merge2 = PatchMerging(dim, norm_layer)
        self.merge3 = PatchMerging(dim, norm_layer)

    def forward(self, x):
        """ Forward function.

        Args:
            x: Input feature, tensor size (B, C, D, H, W).
        """
        x1 = rearrange(x[0], 'b c d h w -> b d h w c')
        x2 = rearrange(x[1], 'b c d h w -> b d h w c')
        gate = rearrange(x[2], 'b c d h w -> b d h w c')
        x1 = self.merge1(x1)
        x2 = self.merge2(x2)
        gate = torch.sigmoid(self.merge3(gate))
        x1 = rearrange(x1, 'b d h w c -> b c d h w')
        x2 = rearrange(x2, 'b d h w c -> b c d h w')
        gate = rearrange(gate, 'b d h w c -> b c d h w')
        return [x1, x2, gate]


class PatchExpand(nn.Module):
    """ Patch Merging Layer

    Args:
        dim (int): Number of input channels.
        norm_layer (nn.Module, optional): Normalization layer.  Default: nn.LayerNorm
    """
    def __init__(self, dim, norm_layer=nn.LayerNorm):
        super().__init__()
        self.dim = dim
        self.expansion = nn.Linear(dim, 2 * dim, bias=False)
        self.norm = norm_layer(dim)

    def forward(self, x):
        """ Forward function.

        Args:
            x: Input feature, tensor size (B, D, H, W, C).
        """
        B, D, H, W, C = x.shape

        # padding
        pad_input = (H % 2 == 1) or (W % 2 == 1)
        if pad_input:
            x = F.pad(x, (0, 0, 0, W % 2, 0, H % 2))

        x = self.norm(x)
        x = self.expansion(x)

        x = x.reshape(B, D, H, W, 2, 2, C//2)
        x = rearrange(x, 'b d h w h1 w1 c -> b d h h1 w w1 c')
        x = x.reshape(B, D, 2*H, 2*W, C//2)

        return x
    

class AllPatchExpand(nn.Module):
    """ Patch Merging Layer

    Args:
        dim (int): Number of input channels.
        norm_layer (nn.Module, optional): Normalization layer.  Default: nn.LayerNorm
    """
    def __init__(self, dim, norm_layer=nn.LayerNorm):
        super().__init__()
        self.dim = dim
        self.expand1 = PatchExpand(dim, norm_layer)
        self.expand2 = PatchExpand(dim, norm_layer)
        self.expand3 = PatchExpand(dim, norm_layer)

    def forward(self, x):
        """ Forward function.

        Args:
            x: Input feature, tensor size (B, C, D, H, W).
        """
        x1 = rearrange(x[0], 'b c d h w -> b d h w c')
        x2 = rearrange(x[1], 'b c d h w -> b d h w c')
        gate = rearrange(x[2], 'b c d h w -> b d h w c')
        x1 = self.expand1(x1)
        x2 = self.expand2(x2)
        gate = torch.sigmoid(self.expand3(gate))
        x1 = rearrange(x1, 'b d h w c -> b c d h w')
        x2 = rearrange(x2, 'b d h w c -> b c d h w')
        gate = rearrange(gate, 'b d h w c -> b c d h w')
        return [x1, x2, gate]
    

class PatchEmbed(nn.Module):

    def __init__(self, img_size=(69,721,1440), embed_dim=96, patch_size=(1,4,4), norm_layer=None):
        super().__init__()

        if img_size[1] % 2:
            self.proj3d = nn.Conv3d(5, embed_dim, kernel_size=(patch_size[0], patch_size[1]+1, patch_size[2]), stride=patch_size)
            self.proj2d = nn.Conv2d(4, embed_dim, kernel_size=(patch_size[1]+1, patch_size[2]), stride=(patch_size[1], patch_size[2]))
        else:
            self.proj3d = nn.Conv3d(5, embed_dim, kernel_size=patch_size, stride=patch_size)
            self.proj2d = nn.Conv2d(4, embed_dim, kernel_size=patch_size[1:], stride=patch_size[1:])

        self.embed_dim = embed_dim
        if norm_layer is not None:
            self.norm = norm_layer(embed_dim)
        else:
            self.norm = None

    def forward(self, x):
        """Forward function."""

        B, C, H, W = x.shape
        x2d = x[:,:4,:,:]  # b,4,721,1440
        x3d = x[:,4:,:,:].reshape(B, 5, C//5, H, W)  # b,5,13,721,1440
        x2d = self.proj2d(x2d).unsqueeze(2)  # b,c,1,180,360
        x3d = self.proj3d(x3d)  # b,c,13,180,360
        x = torch.cat([x3d, x2d], dim=2)  # b,c,14,180,360

        if self.norm is not None:
            D, H, W = x.size(2), x.size(3), x.size(4)
            x = x.flatten(2).transpose(1, 2)
            x = self.norm(x)
            x = x.transpose(1, 2).view(B, self.embed_dim, D, H, W)
        
        return x


class AllPatchEmbed(nn.Module):

    def __init__(self, img_size=(69,721,1440), embed_dim=96, patch_size=(1,4,4), norm_layer=None):
        super().__init__()

        self.patch1 = PatchEmbed(img_size=img_size, embed_dim=embed_dim, patch_size=patch_size, norm_layer=norm_layer)
        self.patch2 = PatchEmbed(img_size=img_size, embed_dim=embed_dim, patch_size=patch_size, norm_layer=norm_layer)
        self.patch3 = PatchEmbed(img_size=img_size, embed_dim=embed_dim, patch_size=patch_size, norm_layer=norm_layer)

        self.patch_resolution = (img_size[0]//5+1, img_size[1]//patch_size[1], img_size[2]//patch_size[2])

    def forward(self, x1, x2, mask):
        """Forward function."""

        x1 = self.patch1(x1)
        x2 = self.patch2(x2)
        mask = torch.sigmoid(self.patch3(mask))
        
        return [x1, x2, mask]


class PatchRecover(nn.Module):

    def __init__(self, img_size=(69,721,1440), embed_dim=96, patch_size=(1,4,4)):
        super().__init__()

        if img_size[1] % 2:
            self.proj3d = nn.ConvTranspose3d(embed_dim, 5, kernel_size=(patch_size[0], patch_size[1]+1, patch_size[2]), stride=patch_size)
            self.proj2d = nn.ConvTranspose2d(embed_dim, 4, kernel_size=(patch_size[1]+1, patch_size[2]), stride=(patch_size[1], patch_size[2]))
        else:
            self.proj3d = nn.ConvTranspose3d(embed_dim, 5, kernel_size=patch_size, stride=patch_size)
            self.proj2d = nn.ConvTranspose2d(embed_dim, 4, kernel_size=patch_size[1:], stride=patch_size[1:])

    def forward(self, x):
        """Forward function."""

        x2d = x[:,:,-1:,:,:].squeeze(2)  # b,c,180,360
        x3d = x[:,:,:-1,:,:]  # b,c,13,180,360
        x2d = self.proj2d(x2d)  # b,4,721,1440
        x3d = self.proj3d(x3d).flatten(1,2)  # b,65,721,1440
        x = torch.cat([x2d, x3d], dim=1)

        return x


class BasicLayer(nn.Module):

    def __init__(self, dim, kernel, padding, num_heads, window_size, sample=None, use_checkpoint=False):
        super().__init__()
        self.sample = sample
        inchans = dim * 2 if self.sample == 'up' else dim
        self.conv = nn.Conv3d(inchans, dim, kernel_size=kernel, padding=padding)
        self.gateconv = nn.Conv3d(inchans, dim, kernel_size=kernel, padding=padding)
        self.gate = nn.Conv3d(inchans, dim, kernel_size=kernel, padding=padding)
        self.crosslayer = GatedCrossAttention(dim=dim, num_heads=num_heads, window_size=window_size, qkv_bias=True, use_checkpoint=use_checkpoint)
        if self.sample == 'down':
            self.samplelayer = AllPatchMerging(dim//2)
        elif self.sample == 'up':
            self.samplelayer = AllPatchExpand(dim*2)

    def concate(self, x, prev):

        x1 = torch.cat([x[0], prev[0]], dim=1)
        x2 = torch.cat([x[1], prev[1]], dim=1)
        gate = torch.cat([x[2], prev[2]], dim=1)

        return x1, x2, gate
    
    def forward(self, x, prev=None):
        if self.sample is not None:
            x = self.samplelayer(x)
        x1, x2, gate = x[0], x[1], x[2]
        if prev is not None:
            x1, x2, gate = self.concate(x, prev)
        
        x1 = F.silu(self.conv(x1))
        gate = torch.sigmoid(self.gate(gate))
        x2 = F.silu(self.gateconv(x2))
        x2 = x2 * gate
        out = self.crosslayer(x1, x2, gate)
        out = [out[0]+x[0], out[1]+x[1], out[2]+x[2]]
        return out
